Method of producing seamless spherical pressure vessels



y 2, 1935- I w. e. HULBERT 'ET AL 2,006,894

METHOD OF PRODUCING SEAMLE S S SPHERICAL PRESSURE VESSELS 7 Filed March 15, 1933- HERE!! Illmllllllill Patented July 2, 1935 PATENT OFFICE METHOD OF PRODUCING SEAMLESS' SPHEBICAL PRESSURE VESSELS William G. Huibert and Joseph A. Thierry, Easton, Pa., assignors to Taylor-Wharton Iron and Steel Company, High Bridge, N. J., a corporation of New Jersey Application March 15, 1933, Serial No. 660,969

Claims.

The object of the invention is to provide a method for the production of seamless spherical metal containers qualified for the reception, eflicient handling and transportation of gases un- 5 der high pressure and of substances which immediately or eventually evolve gases and so generate enormous pressures that can be restrained only by walls possessed of great strength and high resistance forces.

Heretofore, cylinders were used for this purpose for, although,- it was obvious to engineers that the sphere is the ideal construction to withstand internal or external pressures, the manufacturing difficulties were held to be insuperable to insure quantity production of symmetrical or uniformly spherical vessels of the seamless type.

At all events, the spherical metal containers heretofore ofiered to the trade were produced either by casting or by welding and pressure vessels produced by such methods do not possess the proper strength, toughness, and reliability to withstand the service stresses due to the internal pressure of the contained liquids and gases and are not satisfactory to the authorities who frame regulations for the storage, transportation, and handling of compressed gases and other danger- .ous substances.

Our invention overcomes the difficulties previously encountered and insures quantity production of uniformly spherical pressure vessels of the seamless type. 7

The nature, characteristic features, andscope of the invention morereadily will be understood from the following description taken in connection with the accompanying drawing, forming a part hereof, wherein:

Figure l is a sectional elevational view of a die arrangement for the initial operation.

Fig. 2 is a sectional view of the cup resulting from the initial operation.

Fig. 3 shows the crimping operation to provide reverse curves whereby we overcome the tendency to flats of the old practice.

' Fig. 4 shows the next operation of reconciling the outer curve of flare as a step in the, ultimate sphere shaping.

Figs. 5, 6 and '7 show progressive stages of the neck shaping and closing operation.

Fig. 8' shows the finished seamless spherical pressure vessel.

In the practice of the invention we may start with either a billet or plate of carbon steel, alloy steel or any other ferrous or non-ferrous metal which, responds to standard specifications of metals intended for pressure vessels. For the sake of illustration there is shown, in Fig. l, a layout for operation on plate metal, comprising a plunger die 5 and complemental ring dies 5, supported'in a die pot I which has a ledge or shoulder 8 to accommodate the blank or plate metal 9. The action of the dies produces a fairly long cup l0 whereof the bottom is a true hemisphere. This operation and its results are or may be the same as those now used in the manufacture of seamless forged articles, but at this stage we are confronted with the problem which heretofore has baffled engineers and forging experts, namely, to complete the sphere without visible flats.

We solve the problem by crimping, as it were, the cylindrical wall of the cup at a predetermined effective distance from the equatorial axis of the formative sphere. This is accomplished, as shown at H, in Fig. 3, with the result that the crimp is defined by reverse bends or curves, the open end of the article assuming an outward flare and the lower wall of the crimp initiating the sphere V 'finishing operation.

This so-called crimping operation is so uniform in its. results and insures such precision and symmetry that there is a total absence of the hit-ormiss conditions of the old practice of shaping by sight and feel" and, hence, a total absence of flats. The net result is that spherical containers are produced so true to shape and of such even wall thickness as to be perfectly satisfactory to withstand the high stresses to which compressed gas containers are subject in service.

We come now to the next operation of converging the walls of the open end which, as shown at i2, in Fig. 4, involves the inward forcing of the flared wall into reconciliation with the other curvature of the crimped area.

New ensues the action of the dies i3, Fig. 5, which, while maintaining the sphere shaping, initiate the formation of the neck i4; and again, the dies [5, Fig. 6, which operate completely to close and integrate the neck. This operation is followed by the operation, Fig. 7, whereby thebody is trued by dies [6. Manifestly, as is obvious to those skilled in the art, the different opera-- tions may be interrupted from time to time and as may be necessary, to bring the blank up to proper forging or working temperature.

The neck is then cut down to the desired length and bored and tapped for the reception ofa valve and'the result is the seamless spherical pressure vessel shown in Fig. 8'.

what we claim as new, is:- r 1. Method of forming seamless spherical metal pressure vessels, which consists in forge forming a cup whereof the closed end partakes of the shape of a sphere, establishing reverse curves in the wall of the cup an effective distance beyond the equatorial axis of the formative sphere by inwardly directed radial crimping, continuing the body shaping operation by reconciling the reverse curves by a spherical body shaping and closing operation calculated to complete the sphere, the closing being manifested by a solid oilset extension or neck, and boring and tapping the neck for the reception of a valve.

2. The method of forming seamless spherical metal pressure vessels, which consists in forming an elongated cup having a hemispherical closed end, inwardly crimping the side wall of the cup at a predetermined effective distance from the equatorial axis of the formative sphere to initiate the ultimate spherical shaping, removing the crimp by converging the walls of the outwardly flared opening, and continuing the body shaping by subjecting the blank to the action of body shaping and neckingrdies, and boring the neck to provide foningress and egress of pressure.

3. The method of forming seamless spherical metal pressure vessels, which consists in providing a cup whereof the closed end partakes of the shape of a sphere, inwardly crimping the cup an efiective distance beyond the equatorial axis of the formative sphere to initiate closing of is reconciled in coincidence with the inward curvature of the body and continued as a neck. 5. Method of forming seamless spherical metal pressure vessels, which consists in forming by drawing a cup whereof the closed end partakes.

of the shape' of a sphere, establishing reverse curves in the wall of the cup an effective distance beyond the equatorial axis of the formative sphere by inward crimping of the metal whereby the open end of the cup is outwardly flared, continuing the body shaping operation by dieing operations which reconcile the reverse curves and close the body on spherical lines, the excess metal at the closed portion being manifested as a solid oflset or neck, and boring the neck to provide a passway for pressure.

WILLIAM G. HULBERT. JOSEPH A. THIERRY. 

